Raspberry Propagation Methods and the Role of Pollination in Quality Fruit Production
Raspberries can be propagated by seed, runners, suckers, or cuttings. Growing raspberry from seeds is not recommended for commercial production. However, some amateur gardeners harvest the raspberry seeds from ripened raspberries. After harvesting the seeds from a ripe raspberry, they wash them very well to remove any pulp residue (that can decrease germination). Afterward, they place the seeds on paper or in a shallow box and let them dry in the sun. Once they are completely dried, they can be sowed in small pots, covered with a thin layer of soil, and watered. When the seedlings grow, the grower transfers them to larger pots. Avoid placing them directly outside because they need to harden them off.
Propagation of Raspberries by suckers or runners is also very easy. Just dig up the sucker outside the row's width (2 feet or 61 cm diameter) in your garden and plant it elsewhere. Another way to propagate raspberries is by cuttings. When you cut any plant, use a sharp blade or razor dipped in rubbing alcohol to reduce the injury of the parent plant and to prevent transmitting any diseases. You can remove flowers and flower buds to allow the cutting to use the energy for root formation and a rooting hormone to boost the root formation. You can insert the cutting into soil filled with vermiculite or perlite and water them. Choose the most suitable rooting medium to get the best and fastest rooting and keep the soil moist. You can place the root cuttings in a dark place until new shoots form.
The Importance of Pollination for Raspberries
Pollination is essential for raspberry cultivation, as the fruit quality depends heavily on the work of bees. While some raspberry varieties can form fruits without bee visitation, fully developed and market-quality berries rely on proper pollination, affecting the fruit's size, shape, and integrity. Raspberry and blackberry flowers are rich in nectar and pollen, attracting a range of bee species. The fruit of a raspberry comprises multiple drupelets, each requiring pollination to mature fully. If some drupelets remain unpollinated, the berry may become misshapen, crumbly, and less suitable for fresh markets.
Honeybees are commonly used for optimal pollination, but native bees, like some species of Osmia, can be even more effective in pollinating raspberries. These bees ensure better contact with the central pistils, increasing the chances of full fruit development. Raspberry flowers have between 100 and 125 pistils, and each drupelet in the fruit forms around one of these pistils. Without adequate bee visits, drupelets may not develop, leading to poor-quality, deformed fruits. Effective pollination also reduces excess nectar, which, if left unchecked, can attract fungi like sooty mold. Raspberry growers are advised to maintain strong bee hives with robust flight activity and avoid pesticide use during blooming to support healthy bee populations. Generally, the establishment of two hives per acre or 4-5 per hectare is recommended to ensure successful pollination or the raspberry plants.
References
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=2739
Further reading
10 Health Benefits of Raspberries
Interesting facts about Raspberries
Raspberry Plant Information and Variety Selection
How to Cultivate Raspberries Commercially
Raspberry Soil Requirements, Site Preparation and Planting
How to Grow Raspberries from Seed
How to Grow Raspberries in Containers
Raspberries Propagation and Pollination
Raspberry Irrigation: Best Practices for Healthy Growth and High Yields
How to Train and Prune Raspberries